/*
 * Copyright 2002-2016 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.aop.aspectj;

import java.io.Serializable;
import java.lang.reflect.Method;
import java.lang.reflect.Type;

import org.springframework.aop.AfterAdvice;
import org.springframework.aop.AfterReturningAdvice;
import org.springframework.lang.Nullable;
import org.springframework.util.ClassUtils;
import org.springframework.util.TypeUtils;

/**
 * Spring AOP advice wrapping an AspectJ after-returning advice method.
 *
 * @author Rod Johnson
 * @author Juergen Hoeller
 * @author Ramnivas Laddad
 * @since 2.0
 */
@SuppressWarnings("serial")
public class AspectJAfterReturningAdvice extends AbstractAspectJAdvice
        implements AfterReturningAdvice, AfterAdvice, Serializable {

    public AspectJAfterReturningAdvice(
            Method aspectJBeforeAdviceMethod, AspectJExpressionPointcut pointcut, AspectInstanceFactory aif) {

        super(aspectJBeforeAdviceMethod, pointcut, aif);
    }


    @Override
    public boolean isBeforeAdvice() {
        return false;
    }

    @Override
    public boolean isAfterAdvice() {
        return true;
    }

    @Override
    public void setReturningName(String name) {
        setReturningNameNoCheck(name);
    }

    @Override
    public void afterReturning(@Nullable Object returnValue, Method method, Object[] args, @Nullable Object target)
            throws Throwable {
        if (shouldInvokeOnReturnValueOf(method, returnValue)) {
            invokeAdviceMethod(getJoinPointMatch(), returnValue, null);
        }
    }


    /**
     * Following AspectJ semantics, if a returning clause was specified, then the
     * advice is only invoked if the returned value is an instance of the given
     * returning type and generic type parameters, if any, match the assignment
     * rules. If the returning type is Object, the advice is *always* invoked.
     *
     * @param returnValue the return value of the target method
     * @return whether to invoke the advice method for the given return value
     */
    private boolean shouldInvokeOnReturnValueOf(Method method, @Nullable Object returnValue) {
        Class<?> type = getDiscoveredReturningType();
        Type genericType = getDiscoveredReturningGenericType();
        // If we aren't dealing with a raw type, check if generic parameters are assignable.
        return (matchesReturnValue(type, method, returnValue) &&
                (genericType == null || genericType == type ||
                        TypeUtils.isAssignable(genericType, method.getGenericReturnType())));
    }

    /**
     * Following AspectJ semantics, if a return value is null (or return type is void),
     * then the return type of target method should be used to determine whether advice
     * is invoked or not. Also, even if the return type is void, if the type of argument
     * declared in the advice method is Object, then the advice must still get invoked.
     *
     * @param type the type of argument declared in advice method
     * @param method the advice method
     * @param returnValue the return value of the target method
     * @return whether to invoke the advice method for the given return value and type
     */
    private boolean matchesReturnValue(Class<?> type, Method method, @Nullable Object returnValue) {
        if (returnValue != null) {
            return ClassUtils.isAssignableValue(type, returnValue);
        } else if (Object.class == type && void.class == method.getReturnType()) {
            return true;
        } else {
            return ClassUtils.isAssignable(type, method.getReturnType());
        }
    }

}
